Dissipation of heat energy may be accomplished in various ways. Where this heat energy is relatively small, it is quite common to use a body of thermally conductive material to absorb heat from the heated surface and dissipate the heat into the surrounding environment by radiation, convection, etc. Such heat sinks commonly employ thermally conductive fins or pins to increase the surface area of the heat sink exposed to the surrounding environment, thus increasing the efficiency of heat dissipation.
Electronic devices generally produce heat energy which must be removed from the device. Small semiconductor devices, for example, commonly employ a finned heat sink adjacent the device package to remove excess heat. Frequently, large numbers of heat producing devices are employed in an apparatus and thus collectively produce sufficient excess heat to cause serious problems unless effectively dissipated. In such cases it is common to employ a relatively large heat sink body from which extend relatively large area fins.
Since cost and efficiency are the major factors considered, heat sinks are usually made from aluminum or aluminum alloys and, since such materials can be readily and inexpensively extruded as shaped parts, extrusion is usually the preferred method of manufacturing heat sinks. However, where relatively large area, thin and closely spaced fins are desired, extrusion cannot be used. Instead, a heat sink base is formed with closely spaced grooves therein, either by extrusion or other suitable process, and individual plates or fins inserted into the grooves to form a body using large area, thin, closely spaced fins. However, the fins must be physically retained in the grooves and in intimate physical contact with the base in order to provide the heat dissipation required. Thermally conductive adhesives are ordinarily used for the purpose. However, adhesive bonding is time-consuming, labor intensive and expensive. Furthermore, even the best thermally conductive adhesives do not provide the thermal conductivity of unitary or metal-to-metal assemblies.